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Universidad Austral de Chile, Instituto de Botánica, Campus Isla Teja, Casilla 567, Valdivia, Chile
Wolfgang Heyser
University of Bremen, Institute of Environmental Science and Technology (UFT), Plant Physiology and Plant Anatomy, Leobenerstrasse, D-28359 Bremen, Germany
Steffen Härtel
Centro de Estudios Científicos (CECS), Arturo Prat 514, Valdivia, Chile y Facultad de Ciencias Químicas, Departamento de Química Biológica, Pabellón Argentina, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
We determined the location and the activity of surface-bound phosphomonoesterase (SBP) of five ectomycorrhizal (EM) fungi of Nothofagus oblique. EM fungal mycelium of Paxillus involutus, Austropaxillus boletinoides, Descolea antartica, Cenococcum geophilum and Pisolithus tinctorius was grown in media with varying concentrations of dissolved phosphorus. SBP activity was detected at different pH values (37) under each growth regimen. SBP activity was assessed using a colorimetric method based on the hydrolysis of p-nitrophenyl phosphate (pNPP) to p-nitrophenol phosphate (pNP) + P. A new technique involving confocal laser-scanning microscopy (LSM) was used to locate and quantify SBP activity on the hyphal surface. EM fungi showed two fundamentally different patterns of SBP activity in relation to varying environmental conditions (P-concentrations and pH). In the cases of D. antartica, A. boletinoides and C. geophilum, changes in SBP activity were induced primarily by changes in the number of SBP-active centers on the hyphae. In the cases of P. tinctorius and P. involutus, the number of SBP-active centers per µm hyphal length changed much less than the intensity of the SBP-active centers on the hyphae. Our findings not only contribute to the discussion about the role of SBP-active centers in EM fungi but also introduce LSM as a valuable method for studying EM fungi.
Key words: ectomycorrhiza, ELF-97, image processed confocal fluorescence microscopy, P-uptake
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